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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6dd8a3c5f2507d8131cc9facd41b46dfb321c4b4e9bc1e1606ffd8cc478eb2c9' 
  AND token = 'ARiyja9yKSFyAVThK0jTYjtvLjQcV6C3wV7KQsqa0t8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}